Electronic Device

This application is based on and incorporates herein by reference Japanese Patent Application No. 2024-192989 filed on Nov. 1, 2024.

The present disclosure relates to an electronic device including, for example, a chip.

Conventionally, a technique is known in which a heat-generating component such as a semiconductor chip is mounted on a substrate via solder.

According to at least one embodiment of the present disclosure, an electronic device includes a housing, a substrate disposed in the housing, a package component, a heat sink, and load-bearing components. The package component includes a chip and is mounted on the substrate. The heat sink is disposed between the housing and the chip, and joined to the chip. The load-bearing components may be disposed on an extended region of the heat sink where the heat sink extends outward of the package component when viewed in a thickness direction of the substrate. The load-bearing components press the heat sink in a direction from the substrate toward the heat sink.

According to a comparative example, a heat-generating component such as a semiconductor chip is mounted on a substrate via ball-shaped solder (i.e., BGA solder). In this technique, a heat-dissipating member is brought into contact with a surface of the heat-generating component (i.e., a surface facing away the substrate), and the substrate and the heat-dissipating member are integrated with a screw.

As a result of the detailed exploration of the inventor, it has been founded that when the substrate and the heat-dissipating member are integrated with the screw, the heat-generating component and the solder arranged between the substrate and the heat-dissipating member are subjected to a load caused by the fastened screw. Therefore, if an excessive load (i.e., stress) is applied to the solder, the solder may deform, potentially causing a short circuit.

In contrast to the comparative example, according to the present disclosure, an excessive load can be prevented from being applied to a solder.

An electronic device according to one embodiment of the present disclosure includes a housing, a substrate disposed in the housing, a package component including a chip and mounted on the substrate via solder, and a heat sink disposed between the housing and the chip and joined to the chip.

Multiple load-bearing components are disposed on an extended region of the heat sink where the heat sink extends outward of the package component when viewed in a thickness direction of the substrate. The multiple load-bearing components press the heat sink in a direction from the substrate toward the heat sink.

In the present disclosure, such a configuration can reduce an excessive load applied to the solder. In other words, in the present disclosure, the multiple load-bearing components are disposed on the extended region of the heat sink where the heat sink extends outward of the package component. As a result, even when the load-bearing components press the heat sink in the direction from the substrate toward the heat sink, the load is not applied to the solder. Therefore, since the load applied to the solder can be reduced, the solder is less likely to deform, and an occurrence of short circuits due to deformation of the solder can be prevented.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, portions that are the same as or equivalent to those described in a preceding embodiment are denoted by the same reference numerals, and a description of the same or equivalent portions may be omitted. When only some of the configuration elements are described in the embodiment, the remaining configuration elements can be referred from those described in the preceding embodiment. The following embodiments may be partially combined with each other even if such a combination is not explicitly described as long as there is no disadvantage with respect to such a combination.

1 2 FIGS.and 1 3 5 7 9 9 9 11 13 15 As shown in, an electronic device (e.g., electronic control unit)includes a housing, a substrate, an interposer, multiple chips(e.g., chipsA andB), a stiffener, a heat sink, and multiple load-bearing components.

3 17 19 5 3 21 7 5 9 7 9 13 9 15 The housinghas a rectangular parallelepiped shape and includes a box bodyand a lid(i.e., cover). The substrateis secured in the housingby multiple (e.g., four) fasteners (e.g., screws). The interposeris mounted on the substrate. The multiple chipsare mounted on the interposer. The chipsare, for example, semiconductor chips as heat-generating components. The heat sinkis joined to the chipsand is pressed by the load-bearing components.

1 FIG. 1 FIG. 5 5 13 5 19 Hereinafter, as shown in, in a thickness direction of the substrate(i.e., up down direction in), one side of the substratefacing the heat sinkis referred to as an “upper” side, the other side of the substratefacing the lidis referred to as a “lower” side. Additionally, the view in the thickness direction is referred to as an “A view.”

1 FIG. 17 3 23 25 23 17 Hereinafter, each configuration will be described in detail. As shown in, the box bodyof the housinghas an opening on the lower side, and includes a rectangular plate-shaped portionand a side portion. In the A view, the side portion surrounds the plate-shaped portion. The box bodyis, for example, a die-casting product made of an aluminum alloy.

27 23 17 27 23 13 17 27 17 27 27 27 29 31 25 17 3 FIG. A cooling sectionis provided on the lower side of a central portion of the plate-shaped portionof the box body. The cooling sectionhas a rectangular parallelepiped shape, protrudes from the lower side of the plate-shaped portionso as to face the heat sink, and is integrated with the box body. The cooling sectionis, for example, a cooler having a water-cooling structure. Specifically, a portion protrudes downward from the lower side of the central portion of the box body, and this protruding portion serves as the cooling section. A cavity is formed inside the cooling section, and cooling water, which serves as a coolant, is allowed to flow into the interior of the cooling section. As shown in, an inletand an outletfor the cooling water are provided on the side portionof the box body.

1 FIG. 3 FIG. 3 FIG. 33 21 23 17 33 23 33 21 33 a Furthermore, as shown in, four columns(refer to), to which four fastenersare respectively attached, extend downward from a lower face of the plate-shaped portionof the box body. As shown in, the columnsare arranged at four corners of the plate-shaped portion(i.e., at positions corresponding to four vertices of the rectangular shape), in the A view from below. A screw hole, into which a tip end of a fasteneris screwed, is provided at an end of each of the columns.

4 FIG. 19 3 35 17 19 19 37 15 37 37 15 As shown in, the lidof the housingis a plate member which has a rectangular shape in the A view and covers an openingof the box body. The lidmay be made of a material such as an aluminum alloy or iron. The lidincludes four lower-end through-holes. A lower end of each of the load-bearing componentsextends through a lower-end through-hole. The lower-end through-holesare arranged at positions of the vertices of the rectangular shape, corresponding to the positions of the four load-bearing components.

1 FIG. 4 FIG. 19 5 7 13 19 5 7 13 As shown in, since the lid, the substrate, the interposer, and the heat sinkare arranged in this order from the lower side,illustrates a state in which the lid, the substrate, the interposer, and the heat sinkare stacked and viewed from the lower side.

5 5 39 21 5 5 41 15 39 37 41 The substrateis a known printed circuit board (i.e., PCB) and has a rectangular shape in the A view. The substrateincludes fastening through-holes, through which the fastenersare inserted, at four corners of the substrate. Additionally, the substrateincludes load-bearing through-holes, through which the load-bearing componentsextend, at four corners of an area inward of positions where the fastening through-holesare arranged. The lower-end through-holesand the load-bearing through-holescoincide in position with each other in the A view.

2 FIG. 7 9 9 5 7 5 43 45 7 5 7 45 7 5 As shown in, the interposerincludes a wiring electrically connecting between the multiple chips, and a wiring electrically connecting the multiple chipsand the substrate. The interposerand the substrateare electrically connected via solder balls(i.e., BGA solder) arranged in a grid pattern. BGA is an abbreviation of Ball Grid Array. Additionally, a side fillis deposited between the interposerand the substrate, and on a periphery of the interposer. The side fillreinforces a bonding strength between the interposerand the substrate.

11 7 11 7 11 7 11 The stiffeneris mounted on an upper surface of the interposer. The stiffeneris made of a material such as copper, and serves as a reinforcing member to increase a rigidity of the interposer. The stiffenerand the interposerare overlapped with each other in the A view from above. In other words, the stiffenerhas a rectangular-framed shape.

11 11 7 11 7 9 11 7 11 9 47 Specifically, a shape and dimension of the stiffenerare set such that the entire of an outer periphery of the stiffeneris positioned inward of the outer periphery of the interposer. In other words, the stiffeneris slightly smaller in size than the interposer. The multiple chipsare arranged at positions surrounded by the frame-shaped stiffener. Here, this structure, in which the interposer, the stiffener, and the chipsare integrated, is referred to as a package component (e.g., semiconductor package).

1 2 FIGS.and 13 9 49 49 As shown in, the heat sink, having a rectangular shape in the A view, is joined to upper surfaces of the multiple chipswith a joint member(i.e., a solid first heat dissipating member) having heat dissipating performance. The first heat dissipating membermay be made of, for example, solder or a thermosetting adhesive.

13 47 13 47 47 4 FIG. The heat sinkis made of, for example, copper and is deposited so as to cover an upper side of the package component. As shown in, the heat sinkis larger in size than the package componentin the A view, and extends outward of the package componentso as to surround its periphery (i.e., its outer circumference) in the A view.

1 2 FIGS.and 51 13 27 27 27 51 a As shown in, for example, a highly flexible and gel-like heat dissipating member (i.e., a second heat dissipating member)is provided between the heat sinkand the cooling section(specifically, a plate-shaped lower portionthat forms a lower side of the cooling section). The second heat dissipating membermay be made of, for example, a silicone resin, an epoxy resin, or an acrylic resin. These resins may contain fillers having a high thermal conductivity, such as alumina particles.

13 15 13 15 15 15 1 FIG. a b a. Next, a structure in which a load is applied to the heat sinkwill be described. As shown in, the load-bearing components, which are members applying the load to the heat sink, include cylindrical shaft portionsand annular holding portionsprovided along outer peripheries of the shaft portions

4 FIG. 4 FIG. 15 13 15 13 15 13 13 13 47 15 13 a is a view showing positions where the shaft portionspress the heat sink(i.e., cross-hatched circular portions). The load-bearing componentsare disposed at these circular positions (i.e., at positions corresponding to the four corners of the heat sink) in the A view. In other words, the load-bearing componentsare arranged at the four positions corresponding to the four corners of the heat sink. The four positions are located in an area of the heat sinkwhere the heat sinkextends outward of the package componentin the A view (i.e., quadrilateral-framed area with diagonal hatching in). The load-bearing componentsare arranged at the four positions so as to be positioned at the vertices of the rectangular shape of the heat sink.

1 FIG. 15 15 15 41 5 15 15 37 19 15 5 19 53 15 19 a b a b b b As shown in, upper parts of the shaft portionsof the load-bearing components(i.e., portion above the holding portion) extend through the load-bearing through-holesof the substrate, and lower parts of the shaft portions(i.e., portion below the holding portion) extend through the lower-end through-holesof the lid. The holding portionsare disposed between the substrateand the lid, and springsare disposed between the holding portionsand the lid.

53 15 15 15 13 b a Since the springspush the holding portionsupward, the whole of the load-bearing componentsare pushed upward accordingly. As a result, the tip ends of the shaft portionspress the heat sinkupward.

5 5 21 5 47 13 5 Next, a structure pressing the substratewill be described. As described below, the substrateis pressed upward by the fasteners. Additionally, the substrateis placed at a position pressing the package componenttoward the heat sinkin the thickness direction of the substrate(i.e., up-down direction).

1 FIG. 4 FIG. 5 21 33 23 17 55 55 21 39 5 21 As shown in, the substrateis secured by the four fastenersto the four columns, which are erected on the plate-shaped portionof the box body, via washers. The washersare annular members having elasticity (e.g., spring washer or elastic resin). The fastenersare arranged at positions of the fastening through-holeslocated at four corners of the substrate(refer to). In other words, the fastenersare arranged at positions corresponding to vertices of a rectangular shape in the A view.

21 21 21 5 17 21 39 5 33 33 55 a a Each of the fastenersis a screw having a head. The fastenerssecure the substrateto the box bodyby tips of the fastenersextending through the fastening through-holesof the substrateand being screwed into screw holesof the columnsvia the washers.

55 21 5 47 13 5 Since the washersare compressed by the fastenersbeing screwed, the substratecan be slightly moved upward. As a result, the package componentand the heat sinkarranged on an upper surface of the substratecan be pressed upward.

13 15 5 47 21 9 13 Even when the heat sinkis pressed upward by the load-bearing components, the substrate(additionally, the package component) is pressed by the fastenersbeing screwed in a direction where the chipsand the heat sinkbecome in close contact with each other (i.e., upward).

1 1 Next, a method for manufacturing the electronic devicewill be described. The method described below is one example, various manufacturing methods that can manufacture the electronic devicedescribed above are adoptable.

13 9 47 47 5 47 5 43 47 5 First, the heat sinkis joined to the chipsof the package componentusing, for example, solder. In this state, the package componentis disposed on the surface of the substrate, and the package componentis soldered to the substrateby reflow-soldering as well-known. Specifically, the solder ballsare heated and melt to join a wiring of the package componentand a wiring of the substrateto be electrically conductive therebetween.

17 35 5 13 47 17 13 51 51 27 5 51 17 13 Next, the box bodyis placed such that the openingfaces upward. The substrate, to which the heat sinkand the package componentare joined, is placed in the box bodywith the heat sinkfacing downward via the second heat dissipating member. Specifically, the gel-like second heat-dissipating memberis applied to a surface of the cooling section, and the substrateis placed on the second heat dissipating memberin the box bodywith the heat sinkfacing downward.

5 21 15 15 41 53 15 15 53 19 35 17 19 17 15 15 37 19 a a b a Next, the four corners of the substrateare secured with the fastenersbeing screwed. Next, tip ends of the shaft portionsof the load-bearing componentsare inserted into the four load-bearing through-holesof the substrate, respectively. Next, the springsare disposed at rear ends of the shaft portionssuch that the holding portionsare located between the tip ends and the springs. Next, the lidis disposed so as to close the openingof the box body, and the lidis secured to the box bodywith screws or other members that are not shown. At this time, the rear ends of the shaft portionsof the load-bearing componentsare inserted through the four lower-end through-holesof the lid, respectively.

13 9 47 5 In addition to the method described above, for example, the heat sinkmay be joined to upper surfaces of the chipsafter the package componentis reflow-soldered to the substrate. For example, the joining may be carried out by locally heating and melting solder or the like.

1 3 17 5 3 47 9 5 43 13 17 9 9 Next, effects of the first embodiment will be described. The electronic deviceaccording to the first embodiment includes the housing(i.e., box body), the substratedisposed in the housing, the package component(i.e., package component including the chips) mounted on the substratevia the solder balls(i.e., BGA solder), and the heat sink, which is disposed between the box bodyand the chipsand is joined to the chips.

13 47 5 15 13 5 13 47 15 13 53 Furthermore, the heat sinkextends outward of the package componentin the A view, which is viewed in the thickness direction (i.e., up-down direction) of the substrate. The four load-bearing componentsare provided on a surface of the heat sinkfacing the substrateand arranged in the area where the heat sinkextends outward of the package component. The load-bearing componentspress the heat sinkupward with the springs.

43 13 47 13 15 13 5 15 13 5 13 43 43 43 43 With this configuration, the solder ballscan be prevented from receiving an excessive load. In other words, the heat sinkextends outward of the package componentin the A view, and in the extended region of the heat sink, the multiple load-bearing componentsare arranged on the surface of the heat sinkwhich faces the substrate. Therefore, even when the load-bearing componentspress the heat sinkupward in a direction from the substrateto the heat sink, the solder ballsare prevented from receiving the load. Therefore, since the solder ballscan be prevented from receiving the load, the solder ballsare less likely to deform, and an occurrence of shorts due to deformation of the solder ballscan be prevented.

1 5 41 15 41 15 13 41 In the electronic deviceaccording to the first embodiment, since the substrateincludes the load-bearing through-holes, the load-bearing componentscan be disposed so as to extend through the load-bearing through-holes. Therefore, the load-bearing componentscan press the heat sinkvia the load-bearing through-holes.

1 15 15 53 19 15 53 15 13 b b In the electronic deviceaccording to the first embodiment, the load-bearing componentsinclude the holding portions, and the springsare disposed between the lidand the holding portions. Therefore, an elastic force of the springscan press the load-bearing componentsagainst the heat sink.

1 5 21 5 47 13 15 13 13 9 In the electronic deviceaccording to the first embodiment, when the substrateis secured with the fasteners, the substratepress the package componentand the heat sinkupward. Therefore, even when the load-bearing componentspress the heat sink, the heat sinkis less likely to be detached from the chips.

1 13 15 13 15 13 In the electronic deviceaccording to the first embodiment, the heat sinkmay have a rectangular shape in the A view. Thus, the load-bearing componentsmay be arranged at positions corresponding to the four corners of the heat sinkin the A view. Therefore, the load-bearing componentscan press the four corners of the heat sink.

1 9 13 49 In the electronic deviceaccording to the first embodiment, the chipsand the heat sinkcan joined together with the solid first heat dissipating member. As a result, heat dissipating performance is improved.

1 51 13 27 13 27 In the electronic deviceaccording to the first embodiment, the second heat dissipating membercan be disposed between the heat sinkand the cooling sectionso as to be in contact with both the heat sinkand the cooling section. As a result, heat dissipation performance is improved.

1 3 27 13 51 13 27 51 In the electronic deviceaccording to the first embodiment, the housingincludes the cooling sectionat a position facing the heat sinkthrough the second heat dissipating membersuch that a heat can be released from the heat sinkto the cooling sectionvia the second heat dissipating member. As a result, heat dissipation performance is improved.

1 3 5 9 9 9 13 15 15 27 41 47 49 51 53 b Next, a correspondence between the present disclosure and the present first embodiment will be described. An electronic device corresponds to the electronic device, a housing corresponds to the housing, a substrate corresponds to the substrate, a chip corresponds to the chips,A,B, a heat sink corresponds to the heat sink, a load-bearing component corresponds to the load-bearing components, a holding portion corresponds to the holding portions, a cooling section corresponds to the cooling section, through-holes correspond to the load-bearing through-holes, a package component corresponds to the package component, a first heat dissipating member corresponds to the first heat dissipating member, a second heat dissipating member corresponds to the second heat dissipating member, and a spring corresponds to the springs.

A basic configuration of a second embodiment is similar to that of the first embodiment, and hence differences from the first embodiment will be mainly described below. The members with the same names as those in the first embodiment have the same functions. The same reference numerals as those in the first embodiment indicate the same configuration, and reference is made to the preceding description.

6 FIG. 101 103 105 107 103 109 111 107 113 115 117 105 119 117 121 120 123 121 137 109 As shown in, an electronic deviceaccording to the present second embodiment includes, for example, a housing, a substrate, and a package component. The housingincludes a box bodyand a lid. The package componentincludes. for example, an interposer, a stiffener, chips, and is mounted on the substrateby solder balls. The chipsare joined to a heat sinkvia a solid first heat dissipating member. A gel-like second heat dissipating memberis disposed between the heat sinkand a plate-shaped portionof the box body.

125 125 129 111 125 125 125 121 107 125 125 105 111 b a The present second embodiment, similarly to the first embodiment, includes four load-bearing componentsthat have column shapes. The load-bearing componentsare pressed upward by springsdisposed between the lidand holding portionsof the load-bearing components. Similarly to the first embodiment, the load-bearing componentspress the heat sinkupward at positions located outward of the package componentin the A view. Similarly to the first embodiment, shaft portionsof the load-bearing componentsare disposed so as to penetrate both the substrateand the lid.

105 109 105 131 121 105 133 131 In this second embodiment, the substratehas a rectangular shape and is disposed so as to cover substantially an entire interior of the box body. Similarly to the first embodiment, the substrateis secured with four inner fasteners (i.e., screws), which are disposed at vertices of a rectangular shape, so as to surround an outer periphery of the heat sinkin the A view. Furthermore, the substrateis also secured with four outer fasteners (i.e., screws), which are disposed at vertices of a rectangular shape at locations positioned further outward of the four inner fastenersin the A view.

135 131 105 107 137 Specifically in the present second embodiment, heights of four columnsto which the inner fastenersare screwed is set to be slightly less than a distance from an upper surface of the substrate, on which the package componentis mounted, to a lower surface of the plate-shaped portion.

105 135 131 105 107 107 105 As a result, when the substrateis secured to the columnswith the inner fasteners, a central portion of the substrate(i.e., area where the package componentis disposed in the A view) deflects slightly downward. Therefore, the package componentis pressed upward by the substrate.

This second embodiment provides effects similar to those of the first embodiment.

Since the basic configuration according to the third embodiment is the same as that of the first embodiment, the following description will mainly focus on the differences from the first embodiment. The members with the same names as those in the first embodiment have the same functions. The same reference numerals as those in the first embodiment indicate the same configuration, and reference is made to the preceding description.

7 FIG. 201 221 201 203 205 207 207 213 215 217 207 205 219 217 221 220 223 221 227 227 203 225 229 225 221 207 a As shown in, an electronic deviceaccording to the third embodiment is basically the same as that of the first embodiment except for a configuration of a heat sink. Specifically, the electronic deviceincludes components such as a housing, a substrate, and a package component, similar to those in the first embodiment. In detail, the package componentincludes, for example, an interposer, a stiffener, and chips. The package componentis mounted on the substratevia solder balls. The chipsis joined to the heat sinkvia a solid first heat dissipating member. A gel-like second heat dissipating memberis disposed between the heat sinkand a lower portionof a cooling sectionof the housing. In addition, load-bearing componentsare disposed and pressed upward by springs. The load-bearing componentspress the heat sinkupward at positions located outward of the package componentin the A view.

8 FIG. 221 231 233 231 231 233 231 233 Specifically in the present second embodiment, as shown in, the heat sinkincludes a flat portionthat is rectangular plate-shaped in the A view, and a frame portionthat is quadrilateral frame-shaped (i.e., rectangular-frame shaped) and provided at a center of the flat portionin the A view. The flat portionand the frame portionare integrated, and centers of gravity of the flat portionand the frame portioncoincide with each other in the A view.

233 231 207 233 215 233 213 215 217 207 8 FIG. The frame portionprotrudes from one surface of the flat portionin its thickness direction (i.e., surface facing the package component: upper surface in). In addition, a shape of the frame portionin the A view is made similar to that of the stiffener. In other words, the frame portionis disposed along an outer periphery of the interposer(i.e., along the stiffener) in the A view so as to surround components such as the chips, which are disposed in a central portion of the package component.

233 207 215 215 233 217 233 One surface of the frame portionfacing the package componentmay be in contact with the stiffener, or may be spaced apart from the stiffener. The third embodiment has the same advantages as those of the first embodiment. It is preferable that the frame portionis disposed so as to surround an entire periphery of the components such as the chips. However, the frame portionmay also be disposed so as to surround only a part of a periphery of these components.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and various modifications can be made to implement the present disclosure.

303 301 9 FIG. In the embodiments of the present disclosure, the through-holes (i.e., load-bearing through-holes) through which the load-bearing components extend are provided in the substrate. However, instead of the through-holes, notches (e.g., notchof substratein) may be provided in part or in whole. In other words, shaft portions of load-bearing components may be disposed in the notch.

In the present disclosure, the shapes of the substrate or the heat sink may be not only the rectangle but also other polygons. In other words, their planar shapes are not particularly limited.

In the present disclosure, the number of load-bearing components is not limited to four, and two or more of the components may be adopted.

In the present disclosure, the cooling section may be integrated with the housing or may be separate from the housing. If the cooling section is separated from the housing, for example, the housing and the cooling section may be joined so that an appropriate heat conduction is established between the housing and the cooling section.

Multiple functions of one element in the above embodiments may be implemented by multiple elements, or one function of one element may be implemented by multiple elements. In addition, multiple functions of multiple components may be realized by one component, or a single function realized by multiple components may be realized by one component. A part of the configuration of each of the embodiments described above may be omitted. At least the part of the configuration of each of the embodiments described above may be added to or substituted for a configuration of another embodiment.